High Intensity Conditions Research Articles

Long-Term Forecasting of Solar Irradiation in Riyadh, Saudi Arabia, Using Machine Learning Techniques

Forecasting of time series data presents some challenges because the data’s nature is complex and therefore difficult to accurately forecast. This study presents the design and development of a novel forecasting system that integrates efficient data processing techniques with advanced machine learning algorithms to improve time series forecasting across the sustainability domain. Specifically, this study focuses on solar irradiation forecasting in Riyadh, Saudi Arabia. Efficient and accurate forecasts of solar irradiation are important for optimizing power production and its smooth integration into the utility grid. This advancement supports Saudi Arabia in Vision 2030, which aims to generate and utilize renewable energy sources to drive sustainable development. Therefore, the proposed forecasting system has been developed to the parameters characteristic of the Riyadh region environment, including high solar intensity, dust storms, and unpredictable weather conditions. After the cleaning and filtering process, the filtered dataset was pre-processed using the standardization method. Then, the Discrete Wavelet Transform (DWT) technique has been applied to extract the features of the pre-processed data. Next, the extracted features of the solar dataset have been split into three subsets: train, test, and forecast. Finally, two different machine learning techniques have been utilized for the forecasting process: Support Vector Machine (SVM) and Gaussian Process (GP) techniques. The proposed forecasting system has been evaluated across different time horizons: one-day, five-day, ten-day, and fifteen-day ahead. Comprehensive evaluation metrics were calculated including accuracy, stability, and generalizability measures. The study outcomes present the proposed forecasting system which provides a more robust and adaptable solution for time-series long-term forecasting and complex patterns of solar irradiation in Riyadh, Saudi Arabia.

A study of effective exercise methods and resistance intensity for selective strengthening of the infraspinatus muscle

Background To selectively strengthen target muscles, resistance intensity as well as limb position should be considered. Objective This study aimed to identify the most effective exercise positions and the optimal resistance intensity to selectively strengthen the infraspinatus muscle. Methods This study included 18 healthy men who underwent four different external rotation (ER) exercises in prone external rotation (PER), side-lying wiper, sitting external rotation, and standing external rotation (STER) exercise by varying the shoulder positions under low, medium, and high resistance intensity conditions randomly. Infraspinatus and posterior deltoid muscle activities and the infraspinatus to posterior deltoid activity ratio were measured based on ER exercise positions and resistance intensities. Results This study revealed a significant interaction and main effects of exercise position and resistance intensity on muscle activity and muscle activity ratio. Both muscle activities were increased as the resistance intensity increased, but the muscle activity ratio was decreased. Infraspinatus muscle activity and muscle activity ratio were higher in the PER and STER exercises than in other exercises. Conclusion We indicate that PER and STER are effective exercises to selectively strengthen the infraspinatus muscle. Additionally, performing the exercise at low or medium resistance intensity rather than high resistance intensity is recommended to activate the infraspinatus selectively while minimizing the involvement of the posterior deltoid.

Neuromuscular Performance and the Intensity of External Training Load During the Preseason in National Collegiate Athletic Association Division I Men's Collegiate Basketball Players.

Curtis, M, Kupperman, N, Westbrook, J, Weltman, AL, Hart, J, and Hertel, J. Neuromuscular performance and the intensity of external training load during the preseason in National Collegiate Athletic Association Division I men's collegiate basketball players. J Strength Cond Res 39(1): 54-61, 2025-The aim of the study was to determine whether acute changes in neuromuscular performance can be detected through countermovement jumps (CMJs) conducted pre- and postpractice sessions in conditions of high or low intensity measured by microsensors technology. Using an observational repeated measures design, data were collected from 10 male collegiate basketball players. Countermovement jump data were collected before and after practice exposures over 4 weeks of preseason. Select CMJ kinetics were compared in conditions of high and low training load intensity to detect neuromuscular performance changes in displacement of the center of mass and kinetics. Kinetic measures were categorized as output, underpinning, and strategy-related variables. We investigated "output" defined as displacement (jump height [JH]), "underpinning" defined as force-related (mean eccentric force, mean concentric force, force at zero velocity), and "strategy" defined as time-related (countermovement depth [CMD], eccentric duration (EccDur), concentric duration [ConcDur]) variables. There were significant condition × time interactions in CMJ variables namely eccentric mean force (EccForce), force at zero velocity (Force@0), CMDepth, EccDur, and ConcDur. In conditions of high intensity, players had significant, but small decreases in EccForce and Force@0, with small increases in CMD, EccDur, and ConDur, respectively. However, there were no significant decreases in JH. High-intensity practice exposures did not impact neuromuscular performance specific to "output," suggesting that collegiate basketball athletes can maintain JH despite alterations in "underpinning" and "strategy-related" variables. This could have relevance in understanding how fatigue associated with higher-intensity training exposures may potentially alter jump strategy and force production capacities due to external load intensity in collegiate basketball athletes.

Compact non-contact temperature measurement device for high-intensity microwave electromagnetic fields conditions

The practical implementation aspects of heated in microwave electromagnetic fields objects noncontact temperature measurement as one of the main factors in ensuring the quality of the heat-treated product are considered. The advantages of using the pyrometric method of temperature measurement in comparison with the thermocouple method under the influence of high-intensity electromagnetic fields are substantiated. A variant, which includes a cut-off waveguide with fasteners and a small-sized infrared sensor, for continuous temperature measurement system technical implementation of heated in a microwave field objects is proposed. The variants of proposed compact, cheap and versatile temperature measurement unit using a single-zone infrared sensor of the MLX90614 family, in application to conveyor microwave heating installations are described. The convenience of embedding the sensor into the microwave technological installation control system is noted due to the presence of programming functions for the emissivity of the measured object, the possibility of transmitting information about the object temperature using one of two digital protocols, as well as the possibility of building a network of several dozen measuring sensors on one two-wire digital data bus. The small size and weight, simplicity and relative cheapness of the contactless temperature measurement unit design allows it to be used in all types of microwave heating devices.

Performance on a domain-general and a domain-specific cognitive task during exercise: what are the effects of exercise intensity, exercise modality, and time of cognitive assessment among highly-trained athletes?

ABSTRACT This study examined cognitive performance during exercise and the effects of exercise intensity, exercise modality, cognitive task type, and time of assessment, as well as assessed the accompanying self-reported measures. Eighteen highly-trained and elite water polo players (21.04 ± 3.27 years of age; 12 male, 6 female) completed a dual-task protocol on two occasions: once performing a domain-general task (Stroop test with three cognitive trial types) and once performing a domain-specific task (water polo video-based test) during cycling exercise. The exercise involved three work-matched bouts of cycling: continuous moderate intensity, continuous high intensity, and interval high intensity. Self-reported measures (rating of perceived exertion, affect, mental effort, mental and physical demands) were recorded after each exercise condition. There were exercise intensity-related effects on Stroop performance only, including faster reaction time during moderate-intensity exercise for naming trials (p < 0.001), and interactions with cognitive trial type (p = 0.037). There were no differences between continuous and interval high-intensity exercise conditions for either performance or self-reported responses. Notably, mental effort and demand, in addition to physical effort and demand, were perceived to be significantly higher for the Stroop task than for the video-based test despite identical exercise conditions. Furthermore, Stroop accuracy was associated with more positive affect (r = 0.47) and lower ratings of physical demand (r = −0.37). These findings imply possible task-specificity of athletes’ dual-task performance. They also support the importance of further exploring how task duration and participants' perceptions relate to executive function performance during exercise.

Cut Flower Yields and Qualities of Rosa hybrid L. Affected by Supplementary LED Lighting at Night under High Temperature and Low Light Intensity Conditions

Cut Flower Yields and Qualities of Rosa hybrid L. Affected by Supplementary LED Lighting at Night under High Temperature and Low Light Intensity Conditions

Optimization of Hydrogen Production System Performance Using Photovoltaic/Thermal-Coupled PEM

A proton exchange membrane electrolyzer can effectively utilize the electricity generated by intermittent solar power. Different methods of generating electricity may have different efficiencies and hydrogen production rates. Two coupled systems, namely, PV/T- and CPV/T-coupling PEMEC, respectively, are presented and compared in this study. A maximum power point tracking algorithm for the photovoltaic system is employed, and simulations are conducted based on the solar irradiation intensity and ambient temperature of a specific location on a particular day. The simulation results indicate that the hydrogen production is relatively high between 11:00 and 16:00, with a peak between 12:00 and 13:00. The maximum hydrogen production rate is 99.11 g/s and 29.02 g/s for the CPV/T-PEM and PV/T-PEM systems. The maximum energy efficiency of hydrogen production in CPV/T-PEM and PV/T-PEM systems is 66.7% and 70.6%. Under conditions of high solar irradiation intensity and ambient temperature, the system demonstrates higher total efficiency and greater hydrogen production. The CPV/T-PEM system achieves a maximum hydrogen production rate of 2240.41 kg/d, with a standard coal saving rate of 15.5 tons/day and a CO2 reduction rate of 38.0 tons/day. Compared to the PV/T-PEM system, the CPV/T-PEM system exhibits a higher hydrogen production rate. These findings provide valuable insights into the engineering application of photovoltaic/thermal-coupled hydrogen production technology and contribute to the advancement of this field.

Study of curtaining effect reduction methods in Inconel 718 using a plasma focused ion beam.

The curtaining effect is a common challenge in focused ion beam (FIB) surface preparation. This study investigates methods to reduce this effect during plasma FIB milling of Inconel 718 (nickel-based superalloy). Platinum deposition, silicon mask and XeF2 gas injection were explored as potential solutions. These methods were evaluated for two ion beam current conditions; a high ion beam intensity condition (30kV-1µA) and a medium one (30kV-100nA) and their impact on curtaining reduction and resulting cross-section quality was assessed quantitatively thanks to topographic measurements done by atomic force microscopy (AFM). XeF2 assistance notably improved cross-section quality at medium current level. Pt deposition and Si mask individually mitigated the curtaining effect, with greater efficacy at 100nA. Both methods also contributed to reducing cross-section curvature, with the Si mask outperforming Pt deposition. However, combining Pt deposition and Si mask with XeF2 injection led to deterioration of these protective layers and the reappearance of the curtaining effect after a quite short exposure time.

The Thickness Changes of Anatomical Ornamental Monocotyledon Plant Leaves Affected by the Interactions between Plant Types and Light Intensity

The different levels of light intensity affect the anatomical thickness of monocotyledon ornamental plant leaves. The aim of this research was to determine the anatomical thickness of several monocotyledon ornamental plant leaves under different light intensities. The research used a factorial complete randomized design with two main factors, namely plant type and different light intensity, repeated three times. The first factor was the plant type, which consisted of six plant species of monocotyledon ornamental plants which were Chlorophytum laxum, Dracaena reflexa, Rhoeo discolor, Aglaonema commutatum, Cordyline fruticosa and Hymenocallis littoralis. The second factor was light intensity, which consisted of high light intensity (open areas) and low light intensity (shaded areas). The observation was carried out on preserved leaf anatomy made using the paraffin method with modification. The observation variables were the total thickness of the leaf, upper and lower epidermis, mesophyll (for undifferentiated mesophyll), and palisade and sponge (for differentiated mesophyll). Data were analyzed using analysis of variance followed by the LSD test if the treatment was significant. Correlation tests were carried out between total leaf thickness and each leaf anatomical part under conditions of high and low light intensity. The results showed that the interaction between plant types and light intensity influenced the total thickness of the leaves, upper and lower epidermis, and palisade. The plant types independently influenced the mesophyll and sponges, while the light intensity independently influenced only the mesophyll but not the sponge thickness. Hymenocallis littoralis was the only plant that showed thicker under low light intensity, with an increase in the thickness of the upper and lower epidermis. The palisade mainly influenced leaf thickness changes in the differentiated mesophyll.

Model-based optimisation of microalgae growth under high-intensity and high-frequency pulsed light conditions

High-frequency pulsed light is a promising tool to enhance the performance of microalgae cultivation under artificial illumination. The quantitative comprehension of the effects of pulsed light on cell growth is essential to maximise biomass productivity and to increase the efficiency of artificial light for microalgae growth. In this work, a mathematical model is developed to capture the effect of high-frequency and high-intensity pulsed light in photobioreactors. The model extends the formulation proposed by Zarmi et al. 2020 (https://doi.org/10.1016/j.isci.2020.101115) in order to account for the role of the dark time on photoproduction, photoinhibition effects, and the impact of mixing on cell growth in real photobioreactors. High-frequency pulsed light data from steady state and respirometry experiments are used to calibrate the model, which is demonstrated to shed light on the key photosynthetic mechanisms occurring in these extreme experimental conditions. Furthermore, it is shown how the model can be used to identify optimal operation conditions for microalgae growth, which are confirmed and validated by two respirometry experiments. In particular, it is shown that, for a fixed ratio of the light and dark times, a maximum of productivity can be achieved by minimising the dissipation of photons linked to high light conditions. The result paves the way towards a model-based approach to boost microalgae growth via optimisation of high-frequency high-intensity conditions in artificial light illumination.

Effect of high-intensity vibration parameter on droplet transport characteristics in gas channel of proton exchange membrane fuel cell

In aerospace applications, proton exchange membrane fuel cells are subject to high-intensity vibration. Vibration has a substantial effect on water transport in fuel cells. However, there is a lack of research on the effects of multi-directional and high-intensity vibration conditions on fuel cells. In this study, the droplet transport characteristics in the gas channel under high-intensity vibration conditions are investigated for the first time. Moreover, the effects of vibration direction and vibration frequency on the droplet dynamic transport process are specifically studied. The droplet transport state, drainage performance, and pressure drop variation in the gas channel under different vibration conditions are analyzed and interpreted. The results show that low-frequency vibration in the longitudinal direction is more conducive to the droplet discharge, and the pressure drop undergoes a periodic change corresponding to the vibration frequency. Vertical vibration promotes droplet detachment from the gas diffusion layer surface, which contributes to the reduction in water coverage ratio on its surface, despite an increase in the channel pressure drop. Under the influence of horizontal vibration, droplets are more susceptible to adsorption on the channel sidewalls and turn into a liquid film, which leads to a longer discharge time and a reduction in pressure drop.

Conversion of Retinoids along the Marine Food Chain Contributes to Adverse Impacts on the Spine, Liver, and Intestinal Health of the Marine Medaka (Oryzias melastigma).

Marine microalgae serve as an aquaculture bait. To enhance algal cell growth and breeding profits, high-intensity light conditions are standard for cultivating bait microalgae, potentially altering microalgal metabolite production. This research revealed that Thalassiosira pseudonana, when subjected to high-intensity light conditions, accumulated significant quantities of retinal (RAL) that transferred through the food chain and transformed into all-trans retinoic acid (atRA) in marine medaka. The study further explored the toxic effects on individual fish and specific tissues, as well as the mechanisms behind this toxicity. The accumulation of atRA in the liver, intestine, and spinal column resulted in structural damage and tissue inflammation, as well as oxidative stress. It also down-regulated the gene transcription levels of key pathways involved in immune function and growth. Furthermore, it disrupted the homeostasis of the intestinal microbial communities. The implications for wildlife and human health, which are influenced by the regulation of microalgal metabolite accumulation and their transfer via the food chain, require further investigation and could hold broader significance.

High-intensity light promotes adaptive divergence of photosynthetic traits between sun-exposed and shaded populations in Saxifraga fortunei.

Light is essential for plants, and local populations exhibit adaptive photosynthetic traits depending on their habitats. Although plastic responses in morphological and/or physiological characteristics to different light intensities are well known, adaptive divergence with genetic variation remains to be explored. This study focused on Saxifraga fortunei (Saxifragaceae) growing in sun-exposed and shaded habitats. We measured the leaf anatomical structure and photosynthetic rate of plants grown in their natural habitats and in a common greenhouse (high- and low-intensity light experimental sites). To assess differences in ecophysiological tolerance to high-intensity light between the sun and shade types, we evaluated the level of photoinhibition of photosystem II and the leaf mortality rate under high-intensity light conditions. In addition, population genetic analysis was conducted to investigate phylogenetic origins. Clear phenotypic differences were found between the sun and shade types despite their recent phylogenetic origin. The leaf anatomical structure and photosynthetic rate showed plastic changes in response to growing conditions. Moreover, the sun type had a well-developed palisade parenchyma and a higher photosynthetic rate, which were genetically fixed, and a lower level of photoinhibition under high-intensity light. Our findings demonstrate that light intensity is a selective pressure that can rapidly promote phenotypic divergence between the sun and shade types. While phenotypic changes in multiple photosynthetic traits were plastic, genetic divergence in specific traits related to adaptation to high-intensity light would be fundamental for ecotypic divergence to different light regimes.

Alleviation of H2O2 toxicity by extracellular catalases in the phycosphere of Microcystis aeruginosa

High levels of environmental H2O2 represent a threat to many freshwater bacterial species, including toxic-bloom-forming Microcystis aeruginosa, particularly under high-intensity light conditions. The highest extracellular catalase activity-possessing Pseudoduganella aquatica HC52 was chosen among 36 culturable symbiotic isolates from the phycosphere in freshly collected M. aeruginosa cells. A zymogram for catalase activity revealed the presence of only one extracellular catalase despite the four putative catalase genes (katA1, katA2, katE, and srpA) identified in the newly sequenced genome (∼6.8 Mb) of P. aquatica HC52. Analysis of secreted catalase using liquid chromatography–tandem mass spectrometry was identified as KatA1, which lacks a typical signal peptide, although the underlying mechanism for its secretion is unknown. The expression of secreted KatA1 appeared to be induced in the presence of H2O2. Proteomic analysis also confirmed the presence of KatA1 inside the outer membrane vesicles secreted by P. aquatica HC52 following exposure to H2O2. High light intensities (> 100 µmol m−2 s−1) are known to kill catalase-less axenic M. aeruginosa cells, but the present study found that the presence of P. aquatica cells supported the growth of M. aeruginosa, while the extracellular catalases in supernatant or purified form also sustained the growth of M. aeruginosa under the same conditions. Our results suggest that the extracellular catalase secreted by P. aquatica HC52 enhances the tolerance of M. aeruginosa to H2O2, thus promoting the formation of M. aeruginosa blooms under high light intensities.

Preventing Exertional Heat Stroke in Football: Time for a Paradigm Shift.

Among American sports, football has the highest incidence of exertional heat stroke (EHS), despite decades of prevention strategies. Based on recent reports, 100% of high school and college EHS football fatalities occur during conditioning sessions. Linemen are the at-risk population, constituting 97% of football EHS deaths. Linemen heat up faster and cool down slower than other players. Case series were identified from organized, supervised football at the youth, high school, and collegiate levels and compiled in the National Registry of Catastrophic Sports Injuries. Sources for event occurrence were media reports and newspaper clippings, autopsy reports, certificates of death, school-sponsored investigations, and published medical literature. Articles were identified through PubMed with search terms "football," "exertional heat stroke," and "prevention." Clinical review. Level 5. Football EHS is tied to (1) high-intensity drills and conditioning that is not specific to individual player positions, (2) physical exertion as punishment; (3) failure to modify physical activity for high heat and humidity, (4) failure to recognize early signs and symptoms of EHS, and (5) death when cooling is delayed. To prevent football EHS, (1) all training and conditioning should be position specific; (2) physical activity should be modified per the heat load; (3) understand that some players have a "do-or-die" mentality that supersedes their personal safety; (4) never use physical exertion as punishment; (5) eliminate conditioning tests, serial sprints, and any reckless drills that are inappropriate for linemen; and (6) consider air-conditioned venues for linemen during hot practices. To prevent EHS, train linemen based on game demands. n/a.

Temporal changes in temperature-related mortality in relation to the establishment of the heat-health alert system in Victoria, Australia

Extreme heat alerts are the most common form of weather forecasting services used in Australia, yet very limited studies have documented their effectiveness in improving health outcomes. This study aimed to examine the temporal changes in temperature-related mortality in relation to the activation of the heat-health alert and response system (HARS) in the State of Victoria, Australia. We examined the relationship between temperatures and mortality using quasi-Poisson regression and the distributed lag non-linear model (dlnm) and compared the temperature-mortality association between the two periods: period 1– prior-HARS (1992–2009) and period 2– post-HARS (2010–2019). Since the HARS heavily weights heatwave effects, we also compared the main effects of heatwave events between the two periods. The heatwaves were defined for three levels, including 3 consecutive days at 97th, 98th, and 99th percentiles. We also controlled the potential confounding effect of seasonality by including a natural cubic B-spline of the day of the year with equally spaced knots and 8 degrees of freedom per year. The exposure-response curve reveals the temperature mortality was reduced in period 2 in comparison with period 1. The relative risk ratios (RRR) of Period 2 over Period 1 were all less than one and gradually decreased from 0.86 (95% CI, 0.72–1.03) to 0.64 (95% CI, 0.33–1.22), and the differences in attributable risk percent increased from 13.2 to 25.3%. The reduction in the risk of heatwave-related deaths decreased by 3.4% (RRp1 1.068, 95% CI, 1.024–1.112 versus RRp2 1.034, 95% CI, 0.986–1.082) and 10% (RRp1 1.16, 95% CI, 1.10–1.22 versus RRp2 1.06, 95% CI, 1.002–1.119) for all groups of people. The study indicated a decrease in heat-related mortality following the operation of HARS in Victoria under extreme heat and high-intensity heatwaves conditions. Further studies could investigate the extent of changes in mortality among populations of differing socio-economic groups during the operation of the heat-health alert system.

Elaboration of an Economic and Efficient Pulp Conditioning Method for a Low-Quality Coarse Coal Slime

ABSTRACT The high energy consumption of high-intensity conditioning (HIC) limits the popularization of this technology although it has been validated as an effective way to improve flotation. In this study, an economic and efficient pulp conditioning method for a low-quality coarse coal slime was innovatively proposed by comparing four different conditioning-flotation processes. It is found that the energy consumption per unit combustible recovery of conditioning using emulsified diesel was reduced by 8.3% compared with that of the conventional conditioning. This is attributed to the energy reduction of the optimum conditioning speed decreased from 2100 rpm to 1300 rpm, and a negligible energy consumed in the preparation of emulsified diesel. Results showed that when using an emulsified diesel, flotation performance was further improved and less affected by conditioning speed but more by conditioning time. Moreover, flotation is no longer affected by the degree of surface cleaning. It was indicated that the dispersion of collector is crucial for HIC. This study provides a technical reference for the development of economic and efficient conditioning equipment.

The Influence of Nonlinear High-Intensity Dynamic Processes on the Standing Wave Precession of a Non-Ideal Hemispherical Resonator.

The properties of small size, low noise, high performance and no wear-out have made the hemispherical resonator gyroscope a good choice for high-value space missions. To enhance the precision of the hemispherical resonator gyroscope for use in tasks with large angular velocities and angular accelerations, this paper investigates the standing wave precession of a non-ideal hemispherical resonator under nonlinear high-intensity dynamic conditions. Based on the thin shell theory of elasticity, a dynamic model of a hemispherical resonator is established by using Lagrange's second kind equation. Then, the dynamic model is equivalently transformed into a simple harmonic vibration model of a point mass in two-dimensional space, which is analyzed using a method of averaging that separates the slow variables from the fast variables. The results reveal that taking the nonlinear terms about the square of the angular velocity and the angular acceleration in the dynamic equation into account can weaken the influence of the 4th harmonic component of a mass defect on standing wave drift, and the extent of this weakening effect varies with the dimensions of the mass defects, which is very important for steering the development of the high-precision hemispherical resonator gyroscope.

Effect of light intensity on the survival of European spiny lobster (Palinurus elephas) larvae reared in aquaculture system

Light plays a crucial role in the growth, development, and survival of aquatic organisms. To evaluate the survival of European spiny lobster (Palinurus elephas) larvae in relation to different light intensities (26, 359, and 910 lux, equivalent to 0.35, 4.74, and 12.29 μmol·m−2·s−1, respectively), this study monitored the survival rates of reared spiny lobster from the early instar phyllosoma stages to their metamorphosis into the puerulus stage (111 days after hatching) at the three light intensities. The newly hatched larvae were cultured in 65-L Kreisel tanks with 200 individuals each (three replicates per treatment, i.e., light intensity). Phyllosoma stages I to III larvae showed no significant differences in survival rates under different light intensities. However, light intensity did have a significant impact on the survival rates of phyllosoma stages IV and V as well as the metamorphosis of phyllosoma VI into puerulus. The highest survival rates were observed under high and medium light intensity conditions. At the end of the experiment, the highest mean survival rate for stage VI, the metamorphosis into the puerulus stage, was 42.0 ± 2.52 % under high light intensity. These survival rates for reared pueruli were 84 times higher than those achieved in previous studies. The present study results show promise for the successful implementation of commercial scale rearing protocols for European spiny lobster and have implications for the design of crustacean larvae culture systems.

Effects of High-Intensity Inspiratory Muscle Warm-Up on High-Intensity Exercise Performance and Muscle Oxygenation.

An inspiratory muscle warm-up (IMW) improves inspiratory muscle function, but the effects of high-intensity exercise are inconsistent. We aimed to determine the effects of high-intensity IMW on high-intensity exercise performance and muscle oxygenation. Ten healthy men (maximal oxygen uptake [V˙O2max] 52.2 [5.0]mL·kg-1·min-1) performed constant-load exercise to exhaustion on a cycle ergometer at V˙O2max under 2 IMW conditions: a placebo condition (PLA) and a high-intensity IMW condition (HIGH). The inspiratory loads were set at 15% and 80% of maximal inspiratory pressure, respectively. Maximal inspiratory pressure was measured before and after IMW. Oxyhemoglobin was measured in the vastus lateralis by near-infrared spectroscopy during exercise. Rating of perceived exertion (RPE)for a leg was measured after 1 and 2minutes of exercise. Exercise tolerance was significantly higher under HIGH than PLA (228 [49]s vs 218 [49]s, P = .003). Maximal inspiratory pressure was significantly increased by IMW under HIGH (from 125 [20] to 136 [25] cm H2O, P = .031). Oxyhemoglobin was significantly higher under HIGH than PLA at 80% of the total duration of exercise (P = .048). RPE for the leg was significantly lower under HIGH than PLA after 2minutes of exercise (P = .019). Given that oxyhemoglobin is an index of local oxygen supply, the results of this study suggest that high-intensity IMW increases the oxygen supply to active limbs. It may also reflect a reduction in RPE in the leg. In addition, high-intensity IMW may improve exercise performance.